Author Topic: Float bowl drain screws  (Read 857 times)

Online florence

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Float bowl drain screws
« on: December 11, 2025, 01:15:14 PM »
Does anyone know where we can get spare brass screws that go into the float bowl to allow fuel to be drained?  Yesterday my bike was being annoying and misfiring on one cylinder.  I decided to drain the carbs because even with E5, moisture can be present in the float bowls when left too long without running.  The draining procedure worked and when I went to town today it was running perfectly.  I did note, however, the drain screws are quite chewed on my bike and next time I'm doing some maintenance it might be sensible to fit new ones.

Offline DomP

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Re: Float bowl drain screws
« Reply #1 on: December 11, 2025, 01:54:42 PM »
https://ebay.us/m/WMMSPT

Expensive but new
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Online florence

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Re: Float bowl drain screws
« Reply #2 on: December 11, 2025, 02:30:06 PM »
thank you

Offline exvalvesetdabbler

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Re: Float bowl drain screws
« Reply #3 on: December 12, 2025, 11:55:39 AM »

Offline Bryanj

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Re: Float bowl drain screws
« Reply #4 on: December 12, 2025, 06:51:03 PM »
I though nrp had stopped trading

Offline Murf

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Re: Float bowl drain screws
« Reply #5 on: December 13, 2025, 01:48:26 AM »
After many tries I did manage to get through on the phone to them at the beginning of the year, I was after some Keihin carb jets, which they didn’t have and wouldn’t be getting. I seem to remember that the guy on the phone did not seem very interested.

Offline DomP

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Re: Float bowl drain screws
« Reply #6 on: December 13, 2025, 05:40:20 PM »
Im sure it was NRP that i spoke to about resetting my xs650b for its pod filters, its missing the entire filter setup and replacements are near impossible to find for a 1975 and elements if available are extortionate.  The guy seemed reluctant to help insisting I was wasting my time. 
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline Seabeowner

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Re: Float bowl drain screws
« Reply #7 on: December 13, 2025, 07:32:59 PM »
I use a screw with clear tube attached to check fuel height that was sold for a z650, so their thread is the same. And probably others.

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Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange

Offline DomP

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Re: Float bowl drain screws
« Reply #8 on: December 13, 2025, 08:10:04 PM »
Out of interest what pitch is the tread on these?
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline Bloggs

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Re: Float bowl drain screws
« Reply #9 on: December 13, 2025, 08:46:42 PM »
I think it's M6 fine thread. 6 x 0.75
I'll check tomorrow,  I did draw up the screws.
I made replacements with 12mm hex heads and a screwdriver slot. The slots always get damaged so a hex head helps.

Offline Bloggs

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Re: Float bowl drain screws
« Reply #10 on: December 14, 2025, 05:50:02 PM »
Just check my drawing. The threads are M6 Fine, screw has a 12mm diameter head, total length 11mm.

Offline exvalvesetdabbler

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Re: Float bowl drain screws
« Reply #11 on: December 14, 2025, 06:00:48 PM »
[ Guests cannot view attachments ]

Will these do?  found on Aliexpress

Dave

Offline DomP

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Re: Float bowl drain screws
« Reply #12 on: December 14, 2025, 06:55:29 PM »
Ive been trying to find m6 x 0.75 barbed brass hose tails to use to check fuel levels but they seem to all be m6 x 1mm
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline JezzaPeach

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Re: Float bowl drain screws
« Reply #13 on: December 31, 2025, 02:50:36 PM »
Seabeowner, is the height measure screw/tube available somewhere? I did try to make one but not well. I also found that despite very careful measuring (the 22mm) my floats were too high and sucking in excess fuel, ‘soggy’ when blipping down also when idling causing stalling. I lowered them slightly and now she’s running better than ever.
1972 CB500/4 K1 Gold
Wanted: my 500/4 UGP96M
from 1975-78. Garnet Brown.

Offline Seabeowner

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Re: Float bowl drain screws
« Reply #14 on: January 01, 2026, 07:17:53 PM »
Jezza, I got mine from my BIL that he bought for his Z650. Can't find any listed anywhere exactly like it but found these on the bay that may do if you can get them sealed with an O ring.
https://www.ebay.co.uk/itm/353959718217

No just looked again the only do M6 x 1.0 so no go. Keep looking.
« Last Edit: January 01, 2026, 07:23:08 PM by Seabeowner »
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange